Medical device for bone implant and method for producing such a device

Abstract

A bone implantable medical device made from a biocompatible material, preferably comprising titania or zirconia, has at least a portion of its surface modified to facilitate improved integration with bone. The implantable device may incorporate a surface infused with osteoinductive agent and/or may incorporate holes loaded with a therapeutic agent. The infused surface and/or the holes may be patterned to determine the distribution of and amount of osteoinductive agent and/or therapeutic agent incorporated. The rate of release or elution profile of the therapeutic agent may be controlled. Methods for producing such a bone implantable medical device are also disclosed and employ the use of ion beam irradiation, preferably gas cluster ion beam irradiation for improving bone integration.

What is claimed is: 
     
       1. A method of modifying a surface of bone-implantable medical device comprising the steps of:
 forming a plurality of holes in the surface of the medical device; 
 first loading at least one of the plurality of holes with a first therapeutic agent; 
 second loading at least another one of the plurality of holes with a second therapeutic agent that is different from the first therapeutic agent; 
 first irradiating an exposed surface of the first therapeutic agent in the at least one loaded hole with a first ion beam to firm a first barrier layer at the exposed surface in the at least one loaded hole; and 
 second irradiating an exposed surface of the second therapeutic agent in the at least another loaded hole with an ion beam to form a second barrier layer at the exposed surface in the at least another loaded hole, 
 wherein the first barrier layer and the second barrier layer have different properties for controlling elution rate of the first and second therapeutic agents. 
 
     
     
       2. The method of  claim 1 , wherein the plurality of holes are disposed on the surface in a predetermined pattern to distribute the first and second therapeutic agents on the surface according to a predetermined distribution plan. 
     
     
       3. The method of  claim 2 , wherein at least one of the plurality of holes is loaded with a first quantity of the first therapeutic agent that differs from a second quantity of the first therapeutic agent loaded in at least another of the plurality of holes. 
     
     
       4. A method of modifying a surface of bone-implantable medical device comprising the steps of:
 forming one or more holes in the surface of the medical device; 
 first loading at least one hole of the one or more holes with a first therapeutic agent without completely filling the at least one hole; 
 first irradiating an exposed surface of the therapeutic agent in the at least one incompletely filled hole with a first ion beam to form a first barrier layer at the exposed surface of the first therapeutic agent; 
 following the first irradiating step, second loading the at least one incompletely filled hole with a second therapeutic agent overlying the first barrier layer; and 
 second irradiating an exposed surface of the second therapeutic agent in the at least one incompletely filled hole with a second ion beam to form a second barrier layer at the exposed surface of the second therapeutic agent, 
 wherein the first barrier layer and the second barrier layer have different properties for controlling elution rate of the first and second therapeutic agents. 
 
     
     
       5. The method of  claim 1 , wherein the first ion beam is a first gas cluster ion beam and further wherein the second ion beam is a second gas cluster ion beam. 
     
     
       6. The method of  claim 4 , wherein the first ion beam is a first gas cluster ion beam and further wherein the second ion beam is a second gas cluster ion beam.